An adjusting agent of a dialytic solution (hereinafter, referred to merely as "an adjusting agent") is now commercially available in the form of a concentrated solution, as well as a powdery or granular solid agent and may be optionally dissolved in diluting water for adjusting its concentration to be useful for a dialytic solution.
As this type of the dialytic solution, there have been employed bicarbonate or acetate systems. For the bicarbonate system, two types of the adjusting agents, namely one without sodium bicarbonate (hereinafter, referred to as "A agent") and the other sodium bicarbonate per se (hereinafter, referred to as "B agent"), are used. As the solid adjusting agent, there has been mainly utilized the B agent which is the adjusting agent for the bicarbonate system.
When the dialytic solution is prepared from the solid adjusting agent, at first the adjusting agent is generally dissolved in water to form a concentrated solution which is then supplied to an adjusting unit for mixing with additional water to adjust the dialytic solution.
In the adjusting unit for feeding the dialytic solution to a plurality of dialyzers, in order to dissolve and mix the solid adjusting agent in water a conventional procedure has been employed in which a required quantity of water to prepare the concentrated solution necessary for every simultaneous dialysis is stored in a given tank while a plurality of containers (in most cases a transparent bag) each containing the solid adjusting agent is opened by hand, and then the adjusting agent is dosed from all of the containers into a tank for dissolving the same in water by means of mechanical agitation using an agitator (an agitating blade) or the like provided in the tank.
Usually, such dissolving and mixing operation is not carried out in a sanitary atmosphere such as a clean room, and consequently bacteria and dust in the air often come into contact with the adjusting agent and the concentrated solution after dissolution on the one hand, while the opening and dosing operation of the containers should be carried out manually, resulting in many chances of contact with operator's hands on the other hand, which presents a hygienic problem. Further, it is not desirable to leave the concentrated solution for a long period of time after dissolution or to dissolve the agent on the day before use in dialysis and leave it, because of a hygienic problem and possibility of change in concentration of the solution as well. Particularly, the concentrated solution of sodium bicarbonate is relatively unstable and has a short shelf life, so that it should be dissolved and consumed at the time of dialysis. For this reason, the dissolving and mixing operation must be carried out in the busy time before starting dialysis, resulting in a heavy load for an operator engaging in dialysis. Further, much work is necessary for disposal of the remaining solution, a washing procedure of the tank and other steps even after dialysis.
In view of the above, there has hitherto been proposed a continuous saving apparatus for dissolving sodium bicarbonate continuously and automatically (Japanese Patent Publication 1-55893), in which sodium bicarbonate is supplied by a powder-feeding means such as a feeder of powder while water is supplied by a water-feeding means respectively to an agitation tank, and the powder-feeding and/or the water-feeding means may be controlled depending on a concentration of a solution after agitation, thereby dispensing sodium bicarbonate or water to form a concentrated solution of sodium bicarbonate.
Even when the continuous dissolving apparatus of sodium bicarbonate as previously proposed is employed, however, the opening procedure of the vessel containing a necessary amount of sodium bicarbonate for one dialysis and the dosing operation into the storing tank such as a hopper communicating with the powder-feeding means are required. This variant is disadvantageous from the hygienic standpoint, because sodium bicarbonate and the storing tank are contacted with air for long periods of time. Further, there is no disclosure in the patent publication on the automatization and the labor saving for the washing and disinfecting operations of the powder-feeding means.
Accordingly, an object of the invention is to provide a hygienic and labor-saving dissolving apparatus of a powdery or granular, solid adjusting agent for a dialytic solution, which is obviates manual handling and dosing operations of vessels and the agent into a tank, which considerably curtails the time of direct contact of the adjusting agent with impure air, and which allows simple and convenient washing and disinfecting operations for the whole system in contact with a dissolved solution of the adjusting agent.